n体聚集过程和联合聚集过程的集团尺寸分布

本文研究n体聚集过程和联合聚集过程的集团分布演化。从广义Smoluchovki方程出发,给出聚集核K(i₁,i₂,…,i_n)=A sumfrom i=1 to n i₁+B(A,B均为常数)的显解;利用聚集核K(i₁,i₂,…,i_n)=(Ai₁+B)(Ai₂+B)…(Ai_n+B)和核K(i₁,i₂,…,i_n)=A sumfrom i=1 to n i₁+B的方程之间的联系,得出核K(i₁,i₂,…,i_n)=S_(i1)S_(i2)…S_(in)(S_K=AK+B)的凝前解。而且,根据联合聚集动力学方程,讨论了聚集和型核分别为K₂(i,j)=i+j,K₃(i,j,k)=i+j+k的集团尺寸分布C_m(t)的长时行为,并将结论推广到一般的联合聚集过程。 关键词：     

Co2+-Ti4+和Cu2+-Nb5+离子取代BaFe12O19单晶体中Fe3+离子的研究

本文对用Co²⁺-Ti⁴⁺和Cu²⁺-Nb⁵⁺离子取代BaFe₁₂O₁₉单晶体中Fe³⁺离子进行了研究,以Bi₂O₃作为助熔剂生长出了BaFe_12-2xCo_x²⁺Ti_x⁴⁺O₁₉(x=0;0.04;0.09;0.13;0.27和0.68)以及BaFe_12-x[Nb_1/3⁵⁺Cu_2/3²⁺]_xO₁₉(x=0;0.28;0.44和0.60)这两系列的单晶体,测定了100—300K温度范围内样品的磁化强度σ与单轴各向异性常数K₁,我们发现,对Co²⁺-Ti⁴⁺取代的样品,当x≤0.09时,其σ与K₁随x的增加而缓慢增加;当x>0.09时,其σ与K₁随x的增加而迅速降低,至x=1.1时,K₁变为零,对Nb⁵⁺-Cu²⁺取代的样品,其σ值在整个成份范围内基本保持不变,且有缓慢增加趋势;而K₁值则随x增加而单调下降,提出了取代离子在M型六角铁氧体中可能的分布模型来解释我们的结果。 关键词：     

单一多体不可逆聚集方程的解

本文研究的是单一多体不可逆聚集方程的解,从广义Smoluchovski方程出发,分别讨论凝结核为K(i₁,i₂,…,i_n)=const和凝结核为K(i₁,i₂,…,i_n)=sumfrom i=1 to n(i_l)的精确解,求出集团的体积分布C_m(t)。并且还讨论它们的长时行为。 关键词：     

甲烷分子电子碰撞电离和解离的实验研究

本文利用反应显微成像技术(reaction microscope)研究了54 eV电子入射甲烷分子导致的电离解离过程,详细分析了电离解离产生的CH⁺₂,CH⁺,C⁺离子碎片的动能分布情况.实验结果表明,该入射能量下产生CH⁺₂,CH⁺,C⁺离子碎片主要贡献来自2a₁内价轨道电子的直接电离过程产生的离子态(2a< 关键词： 反应显微成像谱仪 电离解离 能量沉积 动能分布     

R2Fe14B(R=Ce,Pr,Gd)磁晶各向异性常数K1,K2随温度的变化

本文在1.5—300K温度范围内测量了R₂Fe₁₄B(R=Ce,Pr,Gd)各向异性常数K₁,K₂和各向异性场H_A随温度的变化。同时用单离子模型计算了Pr³⁺离子对Pr₂Fe₁₄B磁晶各向异性的贡献,得到与实验值半定量符合的结果。 关键词：     

绿色K2-xNaxZn0.94SiO4∶0.06Mn2+荧光粉晶体相变对光致发光性能的影响

采用高温固相法,通过阳离子替代的实验策略,制备出系列窄带发射且颜色可由深黄色调至绿色的K_2-xNa_xZn_0.94SiO₄∶0.06Mn²⁺(0≤x≤2)荧光粉。用X射线粉末衍射仪对样品的物相进行表征,通过扫描电子显微镜和能量色散谱测试对样品的形貌和元素分布进行分析。结果表明,成功地合成了纯相且元素分布均匀的K_2-xNa_xZn_0.94SiO₄∶0.06Mn²⁺(0≤x≤2)荧光粉。在蓝光激发下,随着Na⁺离子逐渐代替K⁺离子,K_2-xNa_xZn_0.94SiO₄∶0.06Mn²⁺(0≤x≤2)荧光粉的发光强度逐渐增强,原荧光粉的发光强度得到有效提高的同时发光颜色由深黄色调至绿色。在427 nm激光的激发下：当x=0.8时,...     

面内场和静态偏磁场作用下条畴和泡畴的稳定性

实验研究面内场H_in和静态偏磁场H_b作用下,(111)面磁泡膜内条畴的消失过程。保持H_b恒定,增加H_in,测量条畴消失场H_s^*和泡畴消失场H_k^*与面内场方向β的变化关系。计及立方磁晶各向异性的影响,建立H_in和H_b共同存在时的条畴稳定性理论。定性解释了实验的主要特点。导出黑、白条畴同时消失时的角度 β_n=1/3(2nπ±arc cos│3/(2^1/2)(M_sH_b)/K₁│)(n=0,±1,±2,…)与实验基本符合。 关键词：     

关于电离真空规测量上限非线性的探讨

在电离真空规的线性测量上限部分,离子流随着压强上升而衰降。这一非线性规律符合非自持放电的理论,并可导出对应于离子流极大值的压强=E/C,其中E为电极间电场强,C为一常数。因此线性测量上限可通过E的增强而得到拓延。通过实验,设计了四种电极间具有较强电场同时又保持较低的灵敏度的电极结构,它们的线性测量上限分别由原来的10^-1托延伸到1托,2托,6托和10托。实验曲线和理论计算数值基本相符。 关键词：     

等离子体中四光子的相干散射

本文应用动力学方法计算了均匀非磁化等离子体的电子二级非线性密度涨落,得到了三波在等离子体中相互作用的三级非线性极化率X⁽³⁾和第四波K₄=K₁-K₂+K₃,ω₄=ω₁-ω₂+ω₃的散射功率,与通常的非相干汤姆逊散射相比,其散射信号要大得多,因此,相干四光子散射可以作为等离子体诊断技术的一个重要方法,本文还指出,文献[4]的结果是本文计算的一个简单情况。 关键词：     

分子部分电子态的高阶振动能级和离解能的精确研究

鉴于K₂分子电子态的振动能谱和分子离解能D_e在实际研究和应用中的重要性,应用Sun,Ren等人提出的基于微扰理论的代数方法(AM)和基于AM的代数能量方法(AEM)研究了K₂分子的X¹Σ⁺_g,a³Σ⁺_u,0^-_g,B¹Π_{u< 关键词： 2}分子')" href="#">K₂分子 代数方法 高阶振动能级 离解能     

Critical Behavior of the Generalized Srnoluchovski's Coagulation Equation

The critical behavior of the gelation of polymers is studied by means of the generalized Srnoluchovski's coagulation equation. The exact solution of the kinetic equation with a factorial coagulation rate R(i₁, i₂, . . . i_n) = s_i1 × s_i2 × . . . × s_in and s_k = A × k + B is derived for the monodisperse initial condition c_m(O) = δ_{m, 1}. It is shown that a gelation transition takes place within a finite time t_c and the gelation time t_c ii characterized by the parameters A and B.     

关于动态位错场张量势的规范变换

本文引入并论证了描述动态位错场的张量势(A与B)的规范交换问题,而且证明这种变换可采取这样的形式:B′=B+▽F, A′=A-ρ?/(?t)▽G,x′=x-ρ?/(?t)F,其中x_i=e_iklA_kl。至于F与G,则为带有很大任意性的时空坐标的矢量函数,但它们要满足以下关系式:F=▽×G,▽²F-1/G_t²-(?²/?t²)F=0.进 关键词：     

High—Temperature Cutoff Approximation of the 3D kinetic Ising Model

A single-spin transition critical dynamics is used to investigate the three-dimensional kinetic Ising model on an anisotropic cubic lattice,We first derive the fundamental dynamical equations.and then linearize them by a cutoff approximation.We obtain the approximate solutions of the local magnetization and equal-time pair correlation function approximation.We obtain the approximate solutions of the local magnetization and equal-time pair correlation function in zero field.In which the axial-decoupling terms γ1γ2,γ2γ3and γ1γ3as higher infinitesimal quantity are ignored,where γα=tanh(2k0633)=tanh(2Jα/kβT）（α=1,2,3,)We think that it is reasonable as the temperature of the system is very high.The result of what we obtain in this paper can go back to the one-dimensional Glauber‘s theory as long as k2=k3=0.     

Excitation of surface plasma waves over metallic surfaces by lasersand electron beams

A laser incident on a metal film (deposited on a glass substrate) from the glass side at a specific angle of incidence, excites a surface plasma wave (SPW) at the metal-free space interface. The ratio of the SPW field to the laser field increases with the laser spot size b attaining a value much greater than one at b>exp(2wα/c) where a is the film thickness and ω is the laser frequency. The SPW (ω, k_z,) can also he excited by a relativistic electron beam, propagating parallel to the interface in the free space region, via Cerenkov interaction when beam energy ϵb=(|ϵ|-1)mc² where ϵ is the effective metal permittivity, and mc² is the electron rest mass energy. When the surface has a ripple of wave number k₀, the SPW (ω, k_zz) can be excited at lower beam energy via sideband coupling, ω=(k_zz +k₀)v_b where v_bzˆ is the beam velocity. In both cases, however, the positioning of the beam in the close proximity of the interface is required. The scheme is useful for the generation of wavelengths longer than 1 μm     

The Generalized Moment Analysis (GMA) and Spin Analysis for Boson Resonances

Our analyais^[1] has shown that there exist sensitive and insensitive regions to determine the spin (J = 2 or 4) of ξ(2230) in the general helicity formalism. Whereaa it just falls into the insensitive region by using current data of ξ. If the number of events is not sufficient it is difficult to determine the spin of ξ^[2]. In this paper we generalize the moment analysis^[3]. We define the photon angular distribution H_J(θ_τ, LM) for the moment of process e⁺ +R^- → J/ψ → τ + ξ, ξ → p + p and the weighted moment by choosing appropriate weight function. They provide an effective criterion to determine the spin of ξ. We also use the method to discuss LIE puzzle for process e⁺ + e^- → J/ψ → τ + B₁ B → P₁ + P₂ + P₃.     

若干高精度恒稳的半显式差分格式

本文构造了解色散方程u₁=au_xxx的若干三层恒稳的半显式差分格式。第Ⅰ、Ⅱ类格式的局部截断误差的阶为O(τ²+h²+(τ²)/(h³));而第Ⅲ、Ⅳ类格式的局部截断误差的阶为O(τ²+h⁴+((τ)/(h))²+τh)。用判别稳定性的Von Neumann准则可证明:第Ⅰ、Ⅱ类格式及当参数α≤1时的第Ⅲ、Ⅳ类格式都是无条件稳定的,并且当必须的边界条件给定时它们可以显式地进行计算。     

阈值附近撕裂模的非线性行为

电阻率型m≥2的撕裂模在线性不稳定性阈值附近的非线性演化方程可以表示为 ?-Q²A+K²/2A²à-Q²(δ△_1e)/(△_1e)A³=0。这里A为模的幅值,Q为线性增长率,K为模的波矢,△_e为线性模匹配计算中的外区解的对数微分差,δ△_1e为非线性效应对于对数微分差的贡献。本文除在拟线性近似下推导出该方程外,还仔细讨论了该模的非线性行为。在对称电流分布sheet pinch模型的特例下,可以证明δ△_1e=0,不存在新的平衡点。 关键词：     

Effect of Saddle-Splay Elasticity on Stability of Disclination Rings in Nematic Liquid Crystals

In this paper, the stability of disclination ring in nematic liquid crystals is studied. In the presence of saddle-splay elasticity (characterized by k₂₄) the disclination ring has a universal equilibrium radius. Depending on the values of the saddle-splay constant k₂₄, the universal equilibrium radius is altered. When k₂₄>0.92k (m=1/2) and k₂₄>0.88k (m=-1/2), the disclination will be a point rather than a ring, where $k$ is the Frank elastic constant in the one-constant approximation.     

CONFINEMENT PROPERTIES OF THE PURE GAUGE FIELDS ON COSET SPACE OF AN ABELIAN CHIRAL GROUP

In this paper the lattice current-current propagator is calcdlated and the influence of coset pure gauge fields of an abelian chiral group G=U₁×U₁⁵ on confinement properties of a quark system is discussed by virtue of the Wilson's criterion in lattice gauge theory. When subgroup H is U₁, the coset pure gauge fields only contribute a perimeter law factor to the current current propagator which has no influence on confinement properties of the system. When subgroup H is U_s, the coset puregauge fields have no influence on wnfinement properties of the system either.     

高压阻塞喷注的湍流噪声

过去曾求得驻点压力（表压）在0.01到10大气压适用的喷注噪声的压力关系。现在将实验扩展到100大气压过热水蒸汽,发现低压时的关系仍然适用,不过由于喷注气体不同,此时多一个附加项20log（M₀/M）,M₀和M分别是空气和喷注气体的分子量;喷注温度则几乎无影响。于是,在与喷注方向垂直,距离喷口1米处的A声级就成为${L_A} = 80 + 20\\log \\frac{D}{{{D_0}}} + 20\\log \\frac{{{M_0}}}{M} + 10\\log \\frac{{{{(P - {P_0})}^4}}}{{{P_0}^2{{(P - 0.5{P_0})}^2}}} + 10\\log \\left[ {\\frac{2}{\\pi }\\left( {{{\\tan }^{ - 1}}{x_A} - \\frac{{{x_A}}}{{1 + {x_A}^2}}} \\right)} \\right]$式中D为喷口直径(mm),D₀为1mm, P和 P₀分别为喷注驻压和环境大气绝对压力,在阻塞时x_A=0.165D/D₀实验证明在较大的温度和压力范围,噪声频谱无甚差别。管道内的扰动可使噪声级提高1-6dBA,对此本文作了理论分析。低压时使 用的小孔消声器在高压下仍然有效,但应注意其特有的关系.